The invention relates to a method for operating a drive device of a motor vehicle, which drive device has a drive shaft, which is operatively connected with at least one wheel of the motor vehicle, a first electric motor, a second electric motor and a manual transmission, wherein for acceleration of the motor vehicle the first electric motor is operated with a first maximal torque and the second electric motor is operated with a second maximal torque. The invention also relates to a drive device of a motor vehicle.
The drive device serves for outputting a torque, for example via the drive shaft. The torque serves in particular for driving the motor vehicle, wherein the drive device provides a torque, which is directed toward driving the motor vehicle, and which acts on the at least one wheel. Correspondingly the drive device can be assigned to a wheel axle of the motor vehicle on which the at least one wheel of the motor vehicle, in particular, however, at least two wheels of the motor vehicle, are provided. The drive device includes two electric machines, i.e., the first electric motor and the second electric motor, which at least temporarily generate the above-described torque together. Beside the two electric machines the drive device includes the manual transmission device.
Known drive devices either have one or multiple electric motors, which are operatively connected with the wheel axle of the motor vehicle or with individual wheels of the motor vehicle. The electric motor or the electric motors are controlled by means of an inverter, which however has a limited power output. For example due to predetermined maximal current strengths and/or predetermined maximal voltages, the inverters or the known drive devices are subject to certain limitations. When only a single electric motor is provided for driving the wheel axle, the power cannot be increased unlimitedly due to the limitations of the inverter. For this reason a respective electric motor can be assigned to the (multiple) wheels of the wheel axle. This increases the available power when both electric motors are operated, however, this also has several functional disadvantages. In particular the entire power can no longer be redirected to an individual wheel, for example by means of torque vectoring.
In addition it is possible to cause multiple electric motors to act on the wheel axle. In case of a direct coupling of the electric motors, however, a rotational speed or a rotary field uniformity has to be ensured by the inverters of the two electric motors. In this case the sum of the power of the electric motors is available on the wheel axle. A disadvantage is, however, that the electric motors always run with the same rotational speed and insofar are always operated at same operating points. As a result at a low overall transmission ratio between the electric motors and the wheel axle or the wheels of the motor vehicle, only a small torque is available at the wheel axle or the wheels.